Engine head



Jan. 5, 1954 R. P. ERNEST 2,664,864

ENGINE HEAD Filed Aug. 3l, 1950 4 Sheets-Sheet lA l N VEN TOR. aer? FE7/776152Z,

R. P. ERNEST Jan. 5, 1954 ENGINE HEAD 4 Sheets-Sheet 2 Filed Aug. 5l,1950 R. P. ERNEST Jan. 5, 1954 ENGINE HEAD 4 Sheets-Sheet 3 Filed Aug.5l, 1950 R. P. ERNEST 2,664,864

ENGINE HEAD 4 Sheets-Sheet 4 Jan. 5, 1954 Filed Aug-, 31, 195o PatentedJan. 5, 1954 ENGINE HEAD Robert P. Ernest, Wayne, Mich., assignor toKaiser-Frazer Corporation, Willow Run, Mich.,

a corporation of Nevada Application August 31, 1950, Serial No. 182,571

14 Claims.

This invention relates to internal-combustion engines and moreparticularly to engine or cylinder heads therefor, wherein a fuelmixture is to be distributed to a plurality of cylinders in aneconomical and eiiicient manner.

In conventional internal-combustion engines it has been customary in thep-ast to attempt t provide means for supplying air-fuel mixture to thecylinders in such fashion that eflicient performance is achieved at highspeeds, and at the saine time the distribution is sufliciently equalizedat low speeds to prevent erratic or inefficient performance when theengine is idling or Warming up. In the conventional rake or gallerytypes of intake manifolds it has been customary, in order to keep thefuel in a proper state of suspension for distribution to the cylinders,to limit the cross-sectional area of the distributor section of themanifold so that especially at idling speeds sumcient velocity ismaintained to prevent en-v trained liquid particles from dropping out ofthe mixture. As alternatives to this expedient, or supplemental thereto,the mixture must be made sufficiently rich, and of sufficiently highintake temperature, so that the cylinder or cylinders il' make themixture too rich for the other cylinders,

decreasing the economy of performance. In order to overcome thesedisadvantages it has been proposed to provide multiple manifolding inthe form of branches which extend from each intake port to, or nearlyto, the riser. However, this design still has the inherent disadvantageof greatly differing passage lengths from the carburetor to the variouscylinders, thus making it diflicult to achieve proper distributionwithout use of the aforementioned expedients.

It is, therefore, an object of present invention to provide a system forsupplying the air-fuel mixture to an internal-combustion engine whichwill achieve equalized distribution of the mixture to various cylinders.and which will keep the fuel in suspension at lower manifold velocities.In association with this object it is Within the contemplation of thisinvention to provide a system which can use a leaner mixture, especiallyat idling speeds and which because lof .the even a greatly improvedoutput and economy of operation.

It is a further object to provide a fuel supply system as described,which will result in a high volumetric efficiency and in which byelimination of the conventional gallery or distributor, relatively largefuel intake passages may be employed without a decrease in theefficiency of distribution at idling speeds.

It is also an object to provide a construction as described above whichby eliminating the conventional application of heat to the manifold, cansupply a fuel mixture to an internal-combustion engine at relatively lowintake temperatures, thus resulting in a denser change and a concurrenthigh mean effective pressure, but which nevertheless has means foreiiiciently distributing and vaporizing heavy fuel fractions whichcollect in the intake system.

It is another kobject to provide an internalcombustion engine having anovel fuel supply system which can be fabricated at a greatly decreasedcost by eliminating the necessity of casting an intake manifold, and inWhich the fuel supply system may be cast integrally with the cylinderhead.

Other objects and advantages of the invention Will become apparent uponconsideration of the present disclosure in its entirety.

The essential features of the invention which achieve the abovedescribed objects comprise an internal combustion engine which entirelyeliminates the conventional intake manifold gallery or distributorcarrying the fuel mixture from av single carburetor, and substitutestherefor a pair of spaced-apart mixture distributing chambers suppliedby a pair of positively linked complete carburetors, each chamber havingconnected thereto a plurality of relatively short radial pas-v sagesleading to the intake ports of one half rof the cylinders. Thesepassages are so designed that they are, as far as is geometricallypossible, of substantially equal length, and each preferably has asection of Venturi shape. The distributing chambers are unheated by theexhaust system, but the end of each passage adjacent its correspondingport is preferably provided with an inclined dam which is heateddirectly from the combustion chamber for insuring completeVvaporization. In a modified form of the invention means are provided forinsuring equalization of the intake pressures, as well as equaldistribution, of.. theV heavy fuel fractions, and a novel exhaustarrangement is provided to cooperate with the intake system.

In the figures:

Fig. 1 is a top plan view of a cylinder head embodying the features ofmy invention, the view 5 being partly cross-sectioned for clarity;

Fig. 2 is a bottom plan view of part of the cylinder head Fig. 3 is :across-sectional' view taken along the line 3 3 of Fig. 1, and showingone of the intake 10 passages;

Fig. 4 is a perspective view of an internal come.. bustion engineembodying the cylinder head` shown in Figs. 1 to 3;

Fig. 5 is a top plan view, par-tlylin cross-section .15

of a cylinder head with a modified intake structure, and having amodiiied exhaust systemint gral therewith;

Fig. 6 is an end view of the cylinder head'slfxowne*2 otherwise:conventional design, .and :constituant-.2.5

by f. standard l methods. .using :conventional: mater-1 rials.: It maybe:sta-tedrthat:altl'xouglrrthe:prirr ciple or.'the;vinvention:isszapplicablef to other; types` :1; of-pcxweneplants-athe inventionrt is.'1;particularlyadapted for use withfour-stroke:xzyciegrfsixecyla -30 index; in-linefenginesp: andi is:`vfurther designed to -be.offespecial advantage'fin engines-:Where:- inthe exhaustmanifold iwould ordinarily. beadiseg posed r oppositeatheiintake systemr.; The cylinder:-

head is, :provided with' a: water iconnection; I 0,: 35

whichrleadsfto, awaterfjacket: I I surrounding.Y the/combustionchambersr Valve`=stem supportsr. I2 .',andro'cker-'arm supports I 3areaprovided -on 1 theupperfvportion. offthe head; In; the embodi-vmentillustrated in Figs. 1 to 4, the-cylinder head:40

is designed to-faccommodate'eJ rake :.typef-of.: exhaust. manifold. (notshown)Y which isconnected to exhaustuportsmM-by.f.means offexhaustpas-ff sages vI5... Bolt .holes eI 6 -are providedfat spaeedf.

intervals alongv therl cylinder headififor f attache` (A4- ingait to theengineblock, andf-asrisy besta-.scene in Figs. 2 and 3 the lowersurfacepf -the :head1:v is providedwith combustionchambersfl'l.-

The i fuel. supply system fcomprisesf. a @pairy c of imixturedistributing-.chambers AIL-onf .theesidal Wall. of..the.: cylinder4vhead opposite ,-.theffexhaust manifold.. These chambers are.ofsubstantially identical V-inwardlyflared v: shape,:.and. lar-,e .diseposedin spacedrelation:- on itheside. .of the'fhead,

each .chamber beine. F'Dr eferably. v cast. Vintegrally ..55

with.. 4the .head.fand adj acent.. `a group J,of -three -1 cylinders.For illustrative. purposes,v eaclrchamber4 .is,.shown as. adapted toreceive thereabove a carburetor ofthe downdraft .,type, although..

the invention is equally` applicableto other types .o

of Vcarburetors. For this' purpose; a flange I9 is provided at the"upper end ongeachJ chamber; having- -bolt holes to' which=a carburetor'21' may' be attacheduas shcwmin YFig". 4.; Each ofitlr'ese"carburetorsfis complete initselfgand theyfareboth adapted-to besimultaneously'controlled by=the= accelerator: pedal,v .the -carburetorsAvlbeing-zvposi-4 tivelyuconnnected by. adjustableflinkage means 1 22:forl this-purpose. Airsupply: connections=23flv andffil'elfsllpplvconnectionsftzrlead torthei-car-i 70 buretors,-these connections-.beingpreferablyi fedi' byA common sourcesg ofgair.; and fuel. respectively'.l It fwilt. thusifbe .rseem that eacha chamber:` -I 8f. lisf`independentlyf'g'supplied Iwitlr:airs-:airefuelz.:` lmix'- tureffromiits?corresponding-searbmetmw;andiv that-75 there can be no mixture flowfrom the carburetor on one side of the engine to the chamber on theopposite side. It will also be observed that no portion of eitherchamber I8 is directly supplied with heat from any source, especiallyfrom the exhaust system as would be customary in conventional intakesystems.

Asstatedpreviously therchambersY I8 are eacht adjacent. afgroup ofthreecylinde'rs; and the arrangement is preferably such that the lineofisymmetry of the chamber is substantially a1igned.-with the centerlineof the middle cylinder'of the group. For example, the chamberIlshownwin'y Fig. 2.is1;substantially aligned with:thefcentral'combustion chamber I1 of the three supplied" by'thatchamber. Each chamber I8 has leadingtherefrom a group of threeintake passages 251" These' passages are in a generallyradlalarrangement with the passage 25a lead- 0 ing to the outer cylinderof each group and the passase..25c..leading5to .'each: inner..cylinder.- be

ingdisposedr .on either. 4fside-of passage 25h leadfing.to.1the-centercylixiden as will-be seen espef cially in Fig;.1. Thepassages` are of a substan .tially uniform length within..thegeometrical; limitseof. design. .andV .eachpassage leads to .an'intakawalve .port .26.. For .this l.purpose the .inf take valve portsarepreferably ,soarranged .that the..ports..for -.the..outer. cylinders Y.of f eachx group are. adjacent the v-centralcylinderxasseen inA Fig. 2,sosthat..passages:'25a.and=25e lie about 30v on either-:sideof .passage25h.. The latter: passage is so designedasto be-curvedthroughoutagreater portion. of.. .its length than .either of passagesj,25a..and,25e,thus..giving.;it atotal length and resistance nearlyequal. .to .thatl .offrits flanking passages.. The inner .surfaces of.passages 25.-are

preferably. .smooth and -..their cross-sectionalarea decreases to. aAnarrow section .N exaggerated in `the .figures for..purposes.of.clarity) and lthen increases .,uniformly., toward .the-valve -ports fora predetermined..distanceVbecoming constant.

thereafter, thus providing-a Venturi effect iin the outer portions..of.the` passages... The-design of the Apassages is such that Lthe Venturieiect v D in each passage will." result .in.uniform.velocities of themixture in allthe passagea.

As isbest seen in Fig'.,.3, the floorof each. passage 25'issubstantially horizontalV outwardly .f of its combustion chamber,.theinner end 4of eachv U passage; adjacent the valv'eport .26.-beingproe vided with an'upwardlyinclined-iloor portionll forming a damfor the collection andQvaporizaf. tion'. of liquid particles'of 'theheavier fractions which.dr.op out. of'the mixture. It will benotedthatzithe 'position of. dam 2l. lis .such .that it. is.

directly at tli'eA source of heat, .namely Y, combustion"'chamber I1.,.so that. fuel collecting.- the. chamber .or the passage. will. fl'wfup.against the- Adam .(o'r to theright. as seen. iniFig. 3). andbe.quicklyvaporizedby rthe .heatedsurface.

In.operation,..airfuel-mxture .Willbe supplied by carburators. 2 I. .to.chambers I8v and .will flow fromleachchambenintofpassages-.Za It willbcI` observed that due to tha-arrangement off'theY passagesvrelativemtochamber I8 av substantially equal famounta of mix-ture Iwill new. intoeach tof i' passages 25u',.-25bl,- and. 25e. SinceA the` passagesareoffsubstantially; equailength 'and have approximately gidenticali-'heat' balances relative to ther'cylinderdieaiithez type'of' mixture`arriving at eacheintalciport 26' will 'be' lvery nearlyY thesameand.'.because7 of thefrelatively short pathVv which-the: -mixturetravels 1 to" arrive at each cyl; inder;;:therev'wilt.be#little:iopportunity for set-v tling out of the entrainedparticles. Any fuel which does collect in the chamber passages will bevaporized upon reaching dam 2`I at the end of the passages. It is thuspossible to design passages 25 of relatively large cross-sectionalareas, to decrease the mixture temperature so as to achieve high output,volumetric efciency and B. M. E. P. and low speciiic fuel consumption.

Table A below illustrates in tabular form the results achieved intesting the novel engine head installed in a stock six-cylinder in-lineengine, the results being compared with equivalent ngures using theconventional manifold together It will be observed from the aboveresults that by use of the intake system described above vastly improvedresults are obtained both in the power output and in the operatingeniciency of va standard engine.

Figs. 5 to 7 illustrate a modified embodiment of the engine head havingan intake system essentially the same as that of Figs. 1 to 4 but havingseveral additional features designed to improve still further theresults achieved by that intake system. As one of said features, each ofthe mixture distributing chambers I8 in Figs. 5 to 7 are provided with apair of ridges 3| and 32 which are aligned respectively with thejunctures 33 and 34 of the intake passages 25. These ridges rise fromthe oor of each chamber I8 a short distance and extend from the outerwall of the chamber, diverging inwardly toward the passages. Thepurposes of ridges 3| and 32 is to distribute equally the heavy fuelfractions which may settle out in chambers I8 before reaching thepassages 25. It will be seen that liquid fuel droplets which settle onany part of the floor of chamber I8 will be held by ridges 3| and 32 inthe i area in which they settle, and since the settling tends to bedistributed evenly over the chamber, each of passages a, 25b and 25Cwill receive substantially equal amounts of liquid fuel. Thisconstruction is especially advantageous when the engine is operating onan incline from the horizontal, since it will be obvious that withoutridges 3| and 32 the liquid fuel would tend to flow toward the lowermostpoint of chamber i8, thus being fed unequally to the three passages 25.

The modification of Figs. 5 to 7 is further vprovided with a tubularaperture 35 within side wall 36 which extends between and connects thetwo mixture distributing chambers I8. The function of this tubularpassage 35 is to equalize the intake depressions between the two halvesof the engine, especially at idling speeds. For this purpose thecross-sectional area of passage 35 is sufciently small to preventsubstantial now of mixture between the two chambers I8, but at the sametime to permit theslight now' necessary to equalize'minor differences-in pressure which mayy occur, thus increasing the smoothness ofoperation of the engine.

The modification of Figs. 5 to 7 is further provided with a novel formof exhaust system which is adapted to cooperate with the manifold systemdescribed above. This system comprises two separate groups of passages,each leading from three adjacent exhaust ports. The passages 31a, 31hand 31o in each group extend in converging fashion from theircorresponding exhaust ports I4 and lead into two spaced-apart exhaustchambers 38 on the side of the engine head opposite rmixturedistributing chambers I8. As best seen in Figs. 6 and 7, the exhaustpassages are upwardly and outwardly inclined, and the chambers 38 areprovided with inclined anges 39 adapted to be secured to the remainderof the exhaust system by such means as a common header (not shown). Itwill be observed that due to the streamlined nature of passages 31 idealflow conditions will be allowed resulting in a minimum back pressure anda minimum of residual gases in the combustion chamber. Due to theconverging nature of the passages and the inwardly ared shape ofchambers 38 it is possible to cast the exhaust system integrally withthe head without danger of cracking the casting. Since each chamber 38draws exhaust from. only three adjacent cylinders, the problem ofreverse ow in the exhaust system is eliminated if the conventional ringorders are used. The system also has the advantage of eliminating theconventional gasket between the exhaust manifold and the head, thusobviating the usual problem of a blown or otherwise damaged gasket dueto expansion of the exhaust manifold under operating conditions.

It will be obvious that other modifications of the invention could beconstructed embodying some but not all of the features shown in Figures5 to 7. For example, a modication containing the tubular aperture 35between the distributing chambers but having a conventional exhaustsystem would be possible. f

I claim:

1. An intake system for a multicylinder internal-combustion engine orthe like, comprising a plurality. of mixture distributing chambers inlongitudinally spaced relation on the engine head, each of saiddistributing chambers .being disposed substantially opposite themidpoint of a group of intake ports, means for mounting a carburetor oneach of said distributing chambers to supply an air-fuel mixturethereto, and a plurality of passagesof nearly equal length within saidengine head and extending from each of said distributing chambers ingenerally radial relation, each of said passages connecting adistributing chamber with one of the intake ports in its correspondinggroup.

2. An intake system for a multicylinder internal-combustion engine orthe like comprising a plurality of mixture distributing chambers inlongitudinally spaced relation on the engine head, each of saiddistributing chambers being disposed substantially opposite the midpointof a group of intake ports, a plurality of passages of nearly equallength within said engine head and` extending from each of saiddistributing chambers in generally radial relation, and means forconnecting an independent carburetor to each of said distributingchambers.

3. In an engine head for a multicylinder internal-combustion engine, anintake system comprising a plurality of mixture distributingchambersinIiongitudinailyfspaxzedirelationomonefsidece* of said enginehead, said distributingtchambers:1:: being-lof inwardiyilaredshap, aplualityiofinsatake' portsffeach'r ofsai'dv distributingvfchaniberszf .ibeingldisposedfisubstantially opposite :vthefzmid-.g 5v poirrtfof agroupof rintake-fportsandsa plurality of passages o't 'nearlyLequallengthewithin :said'en gine'rhe'adl' 'and'iextendingl.from"'eachfoftsaid r dis tributingli chambers finilgenerailyaradialrelation', zz. each'fofsaid passages oonnectmgza distributing .10chamber with one of 'theintake ports inits fcorrespcnding'igroup;wherebyfeach ofasaididistrib-f: utingichambers i distributes '-J themixture s only. tito' its own?grouplofrintakeerports.:

4. iAniintakefsystem toria six-cylinder internal:Y Nv15combustion'en'gine'comprisingra pair of mixture; Tf distributingchambers:inlongitudinaliy::'space relation? on ithelfen'ginehead,y-each'iofisaididist'rib utingchambers being disposed substantiallyoppositea' grcuipiofl threea'dj scent".cylinders;l means:i 20'.; formountingv a earburetori'onfieach.'ofcsaid: dis1-z.- tributingchamberslto supply. lan .air-fuel-fmixture i f Itheretopandthreerpassages pffnearly'equallength' f' extendinglradiallyfromreachroffsai'ddistributing i; chamberswitliinisaid ngineiheadyeachzof said] 225.A passages. connecting a distributingichamberwith fi oneotitlie intake'ports-'iniits correspondingqgroupi 5.'.Inraninginemheadifor a'inulticylinderfinaz ternalcombustionenginlanrintake'systemcorn-a1prisinga.pluralityofmixturerdistributingrcham; --30bersPinlongitudinallyspaced:relation; on'. one'fsideffr ofsaidcenginehead; a mluralit'y of'. combustion -f's chamberstinsaidzffhead, .ea'c'hof said distributing.- chambers beings-disposedsubstantiallyfopposite themidpoint;'ofta-grouproftadjacent:combustion35` chambeislandt a pluralityoff passageso'f nearly". equal length within said engine head andextend-"f: ing fromfiealchm said urlistiibiitingichambers':in:Agenerally'. :radial relationg each of-:saidrxpassages connecting. adistributingwhamberi with' .onerof '.40' the rcombustionchambersfrinitslcorrespondingf: groupgs'whereby each.' of'ssaid 'distributing'eham.-bers-distributes ethernixturefonlyLto its own group of combustionchambers.

6. In an intake system for an internalz-comr-v 45 bustionenginaplurality ofrmixturezdistributing. chambers; in'rspacedleapart'irelationz cn'said- `en-A l y gine; .each of* `said.fchan'ibers being`.adja'cent':'a groupiofzintake portsfaacarburetori operatively fconnected 'toveach'` of 'said chambers," :passages 50- leadingvfrom"e`achi:of 'saidf'chambers 'to leach'cf'f: the intake 'i portsfin"its adjacent rgroup,I .Wl'ierebyl eachiof saidicarburetorswill onlysupply itscore' responding group 'of'ports;fandf ay tubularcony nection"between said chambers; said connection g5' being. 'of fsuicient' sizelf t'ozallow :equalization -of1 pressures within saidfchamberstwhile:preventing substantial mixturet-ow therebetween.;

7. :In ef-head'ffor .an internalcombustionJen`'''V` gine, a plurality ofintake ports;"asplurality"of 30; mixturef= distributing: chambers ein".f'spacedt-apartxi relation? on :said` engine; ieaclr foff. ysaid:chambers being:V adjacent-'fa group: ofrintake'ports, passagesffA`A ofnearlylequal length leading=from"eachofsaid@ chambers tov'each-ofthe'intakeiportsin'itsv adja- YV'65 cent' groupfand aconnection-betweenfsaid:champ: bersfsaid: :connection beings of'sufficient size: to f alloivequalization .of pressures-within said.cham-'cxf bers l .while preventing substantially-.mixture -flow itherebetween.` 70

8.-iIn a headior-an internal-combustionffen.- gine, a plurality ofintake.ports,.a :plurality of. mixture. distributingcharnbers in;longitudinally spaced..relationonifone side wallfot said head, f,passagesiwithin said-head-and leading-ingeneral- 75 1yradialrelation:fromfeachofsaid chambers-:tov:

eachso! thecintake: portsfof :its ".'adj acont Sgroupy;

and :a connectionz=betweemsaid i chambers-'.-withinr said y'side' wall,saidzconnection.; being ofsutcient:

size toallowequalization'offpressures within saidz-.e

chambers"while i. preventing: substantial z-mixturer-'e flowtherebetween;` f

9. AIrran tenginen he'adfiffor a multicylinderintermal-combustionengine, an intake system corn-.:- prisinga plurality'of'mixturedistributing cham#- bers in-`-lorxgitudiriallyrzspaeed'frelationon" one side f of said"V engine: ahead; i fa' plurality'z'of:combustion'nii i in saidhead, a plurality of mixture distributingchambers in spaced-apart relation on said head, a plurality of exhaustpassages in said head, each of said distributing. chambers 'beingremote'from. r said1exhaust-zpassages andsubstantially opposite themid-'point of 'a'group of adjacent combustion chambersand .apluralityfof'. passages extending within said head from each of saiddistributing' chambersxto the :combustion chambersA in its Lcorresponding group; fthei'oorf offeach of said passages :beingsubstantiallyi horizontal outwardly. of

its combustion chamber anda-:upwardlyE inclinedf v adjacent' its`combustion:chamber;l ,f

11. In a cylinder-head foran-internalcombus tion vvengine,"an intake.system .comprising a plurality of'intake ports,^'aplurality#ofaspacedapart i mixture: distributing'*chambers-onrsaidfhead, -each chamberbeing'adjacenta groupfof :intake ports f andthavingasubStantially flatfiloorpa plurality v of passages1;leadingirom' eachyof 1 said-` chambers in generallylradial'.relationftofthe intake'portsin its corresponding grouppand ridgescnfthe -ioor of'.said:chamber:insubstantialalignment with juncIturer.off=adjacent:passagespy whereby :liquid .fuel collecting; on saidfloor .twill :be rguided intosaid paSSageSz 12; Inwa'cylinderffhead-forra sixt-cylinder inter nal combustion engine; six intake ports,4 apair ofr mixture: `distributing :chambers: infspacedfapart- I relationon'cone .sida/of V'saidheadl@each -orsaidl chambers '.befing: v4 ofinwardly: :aredshape/:andl l adjacent-the midpointof a group'ofthreeintakeportsf-threepassagesl leading `from each of said chambersvtoeach' 'ofthe intake-'ports inits corresponding group;v said? passagesbeing. of Anearlyv equal-.length-fand': extending ein v'generally radialf relation within :saldi: cylinder ihead; and two ridges' on the vdoorof each.; offsaid chambers, said ridgesdiuerginginwardlyfand-each'ridgebeing in substantialr-alignment: with-.thef-juncture of adjacentpassages.

13; In' an engine: headfon a multicylinder... internals-combustionengine,.fa plurality .of .intake portsandexhaust ports, a plurality'.of.. mixture distributing -..chambers..in .longitudinally spacedrelation. on one.side.ofl.said engine head, each of said. distributingychambers,y being disposed substantially..opposite.. thef.midpoi11t .of agroup of intakeports,.intakepassages connecting each of said 'intakeports to its corresponding distributing chamber, exhaust passagesleading from each of said exhaust ports to the opposite side of theengine head, said exhaust passages comprising a pluralitj7 of groups,each group extending in generally converging fashion from a group ofadjacent exhaust ports, an exhaust chamber formed at the juncture ofeach of said groups of exhaust passages, said exhaust chambers being inspacedapart relation, and outlets on said exhaust chambers adapted tofeed exhaust gases into a common header.

1li. In a cylinder head for a six-cylinder internal-combustion engine,six intake ports, a pair of mixture distributing chambers in spacedapartrelation on one side of said head, each of said chambers being ofinwardly flared shape and adjacent the midpoint of a group of threeintake ports/three passages leading from each of said chambers to eachof the intake ports in its corresponding group, said passages being ofnear- 10 ly equal length and extending in generally radial relationwithin said cylinder head, and tWo ridges on the floor of each of saidchambers, said ridges dii/erging inwardly and each ridge being insubstantial alignment with the juncture of adjacent passages, thecross-sectional area of each of said passages gradually decreasing andthen increasing toward its corresponding intake port, Whereby saidpassages form venturis for the mixture ow.

ROBERT P. ERNEST.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,464,466 Church Aug. 7, 1923 1,656,051 Fekete Jan. 10, 19281,828,774 Godward Oct 27, 1931 1,842,771 Timian Jan. 26, 1932 2,085,818Messinger July 6, 1937

